The invention concerns a method to evaluate whether a time delay as a implementation dependent parameter is better than a statistically defined soft test limit. The invention is especially applied to a class of measurements measuring the delay time from a cell quality swap, generated by a system simulator, to the registration message, generated by the user equipment, a mobile station for example. In a mobile communication system the mobile station (user equipment) should make a cell reselection or handover to another base station of another communication cell if the quality of communication with the current base station of the current cell (cell quality) decreases and the communication quality with an other base station of an other cell increases over the quality of the current base station.
Such a soft handover handled by a mobile station in a communication system with several base stations for a mobile system of the third generation using Code Division Multiple Access (CDMA) is known from U.S. Pat. No. 5,267,261 for example.
The communication standard defines a maximum delay time (test limit) from the swap cell quality until the time where the user equipment issues a registration message in order to register to the other base station. However, this test limit is not defined as a hard limit, i. e. the user equipment would not fulfil the test requirement if the delay time exceeds the time limit only a single time, but is defined as a soft limit, i. e. the user equipment shall fulfil the test requirement for a certain percentage (for example 90%) of the cases in repeated measurements. The pass fail decision of the user equipment against the soft limit shall be done with a certain quality, for example 5% wrong decision risk.
From the present state of the art it is not known how to deal with such statistically defined soft limits for repeated tests.
It is the object of the present invention to provide an effective method to measure a parameter, especially time delay, against a statistically defined soft limit.